Conventionally, in a patent document 1, an air breather chamber includes an atmosphere communication hole provided above the air breather chamber; and a connection portion formed below the air breather chamber to drain a lubricating oil. With this, the oil flowing into the air breather chamber is smoothly discharged from the connection hole.
However, further improvements have been requested for handling the increase of the amount of the lubricating oil flowing into the air breather chamber.
It is, therefore, an object of the present invention to provide an air breather chamber structure which can attain functions of the air breather chamber even when the amount of the lubricating oil flowing into the air breather chamber is increased.